Aerodynamic rotor



- Sept, 19, 1939. T. ASH

AER (DYNAMIC ROTOR Filed Oct. 10, 1938 Wm) mm @w 6% Patented Sept. 19,1939 v UNITED "STATES PATENT OFFICE 2,173,291 maonimamo no'r'on ThomasLeo Ash, Los Calit' Application October 10, 1938, Serial No. 234,196

17 Claims.

My invention relatesto aerodynamic rotors and the like for lift and/orpropulsion of rotoplanes and other aircraft, and while the inventioninvolvestotally new features it is also in the nature of an improvementupon the rotors set forth in Patent No. 2,108,245 issued February 15,1938, and PatentNo. 2,120,168 issued June '7, 1938.

A particular object of this invention is to provide for using only oneblade which is dynamically balanced; a single blade having the advantageof moving thru relatively undisturbed airwithout interference from otherblades.

By areciprocal action on the part of the blades the rotor shown inPatent No. 2,120,168 provides balance all around or offset balance asand where I thickness and angle of attack of the blade from I jects ofthe invention. Heretofore, speed and efiiciency have been limited byreason of the wing 35 span required for the characteristic'take-ofl andlanding for which rotoplanes are noted. It is an object of this toprovide a wing, or wings, which while having suitable span for customarytakeoff and landing, can be positively retracted to a 40 shorter span inkeeping with some of the objects of the invention.

Specifically, it is an object .of this invention to provide a bladewhich canv be extended to suit landing and take-off requirements butwhich in 45 cruising position-is quite rigid and which is so controlledthru each and every part of each revolution that its centrifugal forceis not employed to hold it in proper position. In fact I provide,

by this invention a blade which in cruising posi- 50 tion is of itselfdecidedly rigid independently of centrifugal force but which is providedwith means for suitably snubbing forces which would otherwise bedamaging to a structurally rigid blade.

55 Other objects and advantages of my-invention will appear hereinafterand will. be better un-- derstood by reason of the order in which'theyappear.

I have illustrated by-the accompanying drawing, one practicalembodiment. In the drawing: 5

Figure 1 is a view mainly in vertical section of such an embodiment.

Figure 2 is a smaller scale plan view of said embodiment; this viewshowing the blade in position for banking to theleft, for example. 10

Figure 3 is a small scale elevation showing the blade in the position'shown by .Figure 2.

Figure 4 is a view in elevation similar to Figure 3 but showing theblade fully extended.

In the embodiment illustrated, and in 'com- 5 mon with Patent No.2,120,168, the wing is made up of. a plurality of telescoping sectionssuch as l, 8; 9, l0 and II respectively and each is provided with anattached cable suchas l2; the wing including the reel I! havinggraduated winding su'rfaces such as 15; one such surface for each cable.The reel includes an integral pinion I6 and is mounted to rotate on afixed shaft l'l.

To rotate the reel positively, as required, any

suitable mechanism, as taught by the prior art may be employed and byway of example I have here shown a rack l8 engaging the'pinion Hi.

This rack is hydraulically driven; there being an integral plunger l9 atone end of the rack reciprocal in a hydraulic cylinder 20. The cablesare 0 so woundon the reel that centrifugal forc acting to pull the wingsections outwardly will rotate the reel so that the pinion acts on therack to move the piston or plunger l9 inwardly of its cylinder 20. Thiswill act to displace oil or the like, contained in the cylinder,outwardly thru the port 2!. Means for controlling the escape of fluidfrom a hydraulic cylinder, and for forcing fluid into such cylinders,are well understood and are not further described or illustrated herein.40 o It will be understood however, that the hydraulically operated reelhere shown will provide for v for this reason and'for purposes-ofbalance, is

extended as at Ia indiametric opposition to the main extent of the wing,and altho in this embi iiiment the rotor may be described as single- 5bladed, this extent 10 does do some lifting, as will appear hereinafter.l

The true center of rotation of the wing or blade is located inwardlyfrom extension la and at the center of rotation and on the 'under side,the blade, at section I, is provided with a pivot shaft 22 which ismounted within a boss 23 forming an integral part of the wing section I.This provides for the wingpivoting on an axis right-am gular to thelongitudinal axis of the wing. While such pivot has been provided inprior aircraft to provide for automatic coning or for positive coningthru the aid of mechanical devices, .I provide this pivot as part of asnubbing device which prevents undue strains on the root section of thewing.

Another part of the snubbing. device is provided in the form of acounter-weight W carried at the outer end of a cable 25. This cable iswoundupon a special winding surface 25a, also provided by the reel I4,and this winding surface provides that for any position to which thewing sections are extended, the cable 25 will have correspondingunreeled length and thru centrifugal force will provide for dynamicallybalancing the single wing. This cable extends out from extension !a thrua tube 28; which tube is downwardly directed to hold the cable 25 andweight W at a plane of rotation lower than that of the wing.. This notonly prevents the cable from moving in the same plane, and thru the sameair, thru which the wing moves, but it causes the weight W to act at alltimes during rotation to keep the wing in a nearly level "or horizontalposition. Therefore, no stops are needed for the pivot 22. Thus theweight W not onlyacts as a balance for the single wing, but it alsoprovides the aforesaid snubbing device to protect the otherwise quiterigid wing from sudden stresses which might produce a twist or shear atthe root section 1. Also the combination of the pivot 22 and the weightW provides an ideal means for suspending aircraft from a rotary wing orlifting system.

The numeral 21 indicates a part, either the- 29. This shaft, below themember 21, is provided with a set of bevel gears, indicated at 30, whichconnect the shaft 29 with a power shaft 3|; it being understood that in.rotoplanes the rotor is started by power. I further propose to use thisshaft 3| and gears 30, at times, to connect the rotor of such a craft(with the usual propeller)- to apply any excess turning effort of therotor to use inproviding a long and otherwise powerless glide.

The rotor shaft is provided at the upper end with a bracket 32 in whichthe pivot 22 is carried so that while the wing may pivotit is connectedto the rotor shaft for positive rotation therewith. Altho the wing beingdescribed provides for meeting various loads by being extended asrequired and does not depend, as do prior rotors, for

changing angle of attack, I have shown the pivot,

shaft 22 as having right-angular extensions or arms 34'mounted to pivotin bracket 32 so that the angle ofattackof the wing may be changed ifdesired. For instance, to show the efficiency that when the, craft isinverted the angle of attack will be efiective positively. Also I showthis type of pivot to remind those skilled in the art that the weight Wmay be positioned so that it will act to control angle of attack. Theweight may have any suitable cross sectionand this section may be suchas to give either positive or negative lift, but of course minimum dragis important. In'Figures 2, 3, and 4 respectively, it.

\ and it is a feature'of the invention that when the blade is soextended it will cone slightly to give stability during landing, takeoffand slow speed,

while in Figure 3 the blade is shown about onehalf retracted.

This partially retracted position provides inherent structural rigidityon the part of the blade and while the shortened wing provides therequired lift at cruising speed it offers much less drag than were thewing required to be always extended to the span "required for landingand take-ofi'. In the embodiment illustrated the action of weight W atthe regular cruising speed is such as-to permit little or no coning onthe part of the relatively rigid short blade, altho this same weight andthe pivot do allowfor coning in an emergency where a rigid non-coningblade might be damaged.

Pivotal mounting of the blade in combination with the action of weight Wis particularly advanta'geous in take-off where the blade is firstrevolved by power and then suddenly expanded to provide a suddenvertical ltake-ofi, for under those conditions this blade, which ofitself is quite rigid, will be suddenly subjected to reactions fargreater than the weight of the aircraft.

It will be apparent now that I have provided a blade which isstructurally rigid and which does not depend upon its centrifugal forceto keep it suitably rigid, but which blade is so mounted and socontrolled by the weight W that it will pivot under extreme load orsudden changes of air density. Thus the advantages of a rigicibladev areenjoyed while the previous disadvantages are overcome. As compared withprior aircraft of the type to which this invention more particularlyrelates, the reduced drag of the blade and the higher speeds madepossible by this invention,

which encloses those parts of the wing in the vicinity of the center ofrotation and this hub is movable to, and adapted to be held in, any

eccentric position, such as the position in which it is shown in Figures2, 3 and 4. In Figure 1 it is shown fully concentric with the center ofrotation. 4

The means for shifting the hub comprises an arm III which passes up thruthe hollow of the hollow rotor shaft, then thru the pivots, then thruthe wing section! where it is supported revolubly by opposed thrustbearings ll and 42, and

Vance, where the blades project as at 43a, to permit of -the blade beingtilted without the hub being tilted. Within the hollow ofthehub, andabove the wing, there is provided a hydraulic cylinder 44, fixed to thehub as at a. This cylin- 50. by a link 52. Thus increases the wingsections tend der is horizontal as is the arm 40, which .arm' turns at40c and after passing into the cylinder, terminates in a plunger 45. Thearm is hollow.

thruout and at the lower end is enlarged to pro-' vide a secondhydraulic cylinder which, thru the hollow arm 40' communicates with thebore of the cylinder 44.

A bracket 48 is connected rigidly to the cyl-.

.inder l6 and to this bracket is pivoted, as at 49,

a lever;50. This lever is in reality the stick" by which the craft iscontrolled. Withinthe cylinder 46 is a plunger 5| connected to the leverwhen the outer end 50a of the lever is depressed, fluid contained incylinder IE will be displaced thru the hollow of arm 40 into cylinder46.

The hub, or at least a portion thereof, is nonrotative so that the arm40 maybe pointed in any direction and held there. Accordingly the lowerpart 39b of the hub is provided with an annular bearing 54 so that it'may turn within the hub and rotate with the wing.

While the operation of some parts has been de scribed herein, theoperation of the-rotor as a 'whole'will be understood fromthe'following:

With'all parts in the idle position indicated by Figure 1 take-off maybe accomplished by power rotation of the rotor shaft. As the rotativespeed to fly outward, restrained by fluid in the cylinder. When suit-"able rotative speed is reached the sections. are allowed to move out. Ifthis is done suddenly and the wing expanded to full span'the liftbecomes considerably greater than the weight of the craft to which it isattached and a rapid rise or takeoff will result. As soon as theaircraft is under way the wing may be contracted to a span justsufficient to sustain the craft while setting up the minimum of drag.Since the root section I, and the extension Ia where it projects fromthe hub, has as much lift per unit of length as do other sections, thewing is eflective right down to the hub.

It will be found that for level flying under normal conditions aslightly eccentric position of the hub will provide aerodynamic balanceso that .the wing will show equal lift in all partsof the disc area andthere will belittle or no tendency for the wing to fflap. In fact thisrigid wing is not designed to flap and will not even tilt on its pivot,or cone, except under a temporary load greater than that found in normalflight at cruising speed. Whenever the blade is expanded or contractedthe weight moves in or out accordingly, since its cable is wound on thesame reel as that upon which the blade-section cables are wound. Thusdynamic balance is alwaysprovided.

To bank the aircraft to make a turn, or to nose it up in a climb, ordown in a dive, the stick is turned to point in the desired. directionThus in Figure 1 it is shown pointing to the left, which means-thatcylinder 44 is pointing in the same direction. Now, by depressing thestick slightly the cylinder 48 and its plunger act as a pump to movefluid in to cylinder 44 to thus move the hub in that direction away fromthe center of rotation blade sections. It will be seen from this thatsection I while passing thru the right-handside of the disc area isfully effective in producing lift while section or extension la is alsoeffective in producing lift when passing thru the right-hand part of thediscarea. However, both of these are moved into'the hub and are quiteineffective when passing thru the left-hand part of the disc area.Accordingly the wing has much greater lift on the'right-hand portion andthis will cause the craft to bank and turn to the left; just as isindicated by the stick. A right-hand turn, a climb, or a dive may bebrought about in'the same manner by swinging the stick around-to pointin the desired direction while depressing the. outer end of the stick.Raising the end of the single-blade or multi-bladed wing may be usedwith other means for snubbing.

This disclosure will suggest to those'skilled in the art many othermodifications, suchas employing some of the features .of this inventionin a flexiblewing, altho I hold that I am first in the art' to make itreally practicable to employ a blade which isdecidedly rigid; which doesnot tend to flap because it is aerodynamically bal-- anced all aroundthe discarea; and which blade has increasing rigidity with increase ofspeed by reason of the fact that it can be retracted to such span foreach speed and load combination as to give just the right lift withminimized drag. Also in quick'vertical take-off. rigidity of the wingorblade is not'a detriment since snubbed coning can take place. Also thisinvention results in a further advantage from using blade sections ofincreasing chord," thickness and angle of attack inwardly; thisproviding uniform lift from root to tip and evenly distributing the loadso that rigidity becomes an advantage ratherthan a disadvantage.

tend to vibrate very slightly but it will beseen that the hydraulicshifting means for same provides a non-positive connection between thehubv and the rest of the assembly so that dynamic balance as a whole isnot altered. It. willalsobe understood that the invention applies toapropeller as well as to a lifting rotor, and may also be applied tofans and other I claim: v

1. In a rotor of the class described, an airfoil blade comprising aplurality of telescopically associated airfoil sections of increasingchord, thickness and angle of incidence respectively inwardly of theblade whereby the blade has substantially constant lift per unit of span'from'the' tip to ,approximately the center of rotation, a movable hubnormally co-axial to the center of rotation 75 I aerodynamic rotors.

A further advantage of having the root section equally as effective asthe other sec-.

of said blade and enclosing the blade for an appreciable distanceoutwardly from its center of rotation, and means for eccentricallyshifting said hub.

2. The rotor as is claim one and including means operable duringrotation of 1 said blade and independently of said hub-shifting meansfor contracting said blade against centrifugal force.

3. The rotor as in claim one and in which said hub includes aplatesuperposed immediately over said blade, and said shifting means includesan extension element for said plate radial to the-center thereof andmeans for moving the element radially about the center of rotation ofsaid blade.

4. The rotor as in claim one and further including, a winding reelcarried in the innermost section of said blade and provided with aplurality and attached to each .wing section of graduated windingsurfaces, cables, one for and each wound on a corresponding windingsurface.

5. The rotor as in claim one andfurther including a stub-end to theinnermost section of said blade projecting radially from the center ofrotation of said blade in diametric opposition to other parts of theblade, a centrifugal weight and a cable connecting said weight to saidstub-end.

6. The rotor as in claimone and in which said last named meanscomprises; means for turning said hub about the center of rotation ofsaid blade, and meansfor moving the hub radially outward with respect tosaid center of rotation.

'7. In a rotary lifting system for aircraft, a centralrotary shaft, asingle airfoil blade carried by said shaft extending approximatelyradially thereof, a cable extending radially with respect to said shaftfrom the inner end of said blade in diametric opposition thereto, and arelatively small area weight carried at the outer end of said cable toprovide dynamic balance.

8. The system as in claim seven and including means for contractingsaid-wing and for winding in said cable co-ordinately to providemaintained dynamicbalance.

9. The system as in claim seven and in which said cable and said bladeare disposed. to move in 'planes of differing elevations.

10. The rotary lifting system as in claim seven and in which said bladeis structurally rigid and pivoted to said shaft so as to be free tocone; said cable connected to said blade so that the centrifugal forceof the weight tends to resist coning of the blade.

11. The system as in claim seven in which said blade comprises aplurality of blade sections.

telescopically associated so as to provide rigidity independently ofcentrifugal force.

12. In a rotary lifting system central shaft, a blade section projectingradially for aircraft, a

winding reel, a motor housed in said first section for'rotating saidwinding reel, a second cable wound on said reel and section outwardly indiametric opposition to the sections, and a weight connected at theouterend of said cable acting to dynamically balance said sections.

- 13. The rotary lifting system as in claim twelve and including a pivotconnecting said inner section with said shaft to allow said sections tocone; said weight and corresponding cable acting under centrifugal forceto resist such coning.

l4. The rotary lifting system as in claim twelve and including aneccentrically shiftable hub enclosing the inner 'end of said firstsection normally co-axial with said shaft, and means for shifting saidhub eccentrically of the center of rotation of said sections.

15. The rotary lifting system as in claim twelve and further including afreely floating hub en-. closing the inner end of said first section, asecextending thru the first ond shaft within the first shaft supportingsaid hub and adapted to be turned, a piston projecting horizontallyradially from said second shaft, a cylinder carried by said hub andcontalning'said piston, means for turning said second shaft andmeans'for injecting fluid into said cylinder.

16. In an aerodynamic rotor, a shaft, a single blade projecting from anddriven by said shaft,-a hub normally tions of said blade, and means formoving said hub axially of said blade and for then constraining said hubto rotate with said blade around a point eccentric to the shaft.

17. In a rotary lifting system for aircraft, a hu a single bladeprojecting radially from said hub, a dynamic balance weight for saidblade, -a cable extending from said hub in diametric opposition to saidblade and connected at its outer end to said weight, said systemincluding means operable once during each revolution of said blade toretract said blade relatively inwardly of said hub during apredetermined part of each revolution and to allow said blade to moverelatively outwardly of saidhubduring other portions of the revolution;said means acting to move said cable relatively outwardly of said hubwhen said blade is being moved inwardly relatively thereof, and to movesaid cable relatively inwardly of said hub when said blade ismovingrelatively outwardly of said hub.

\ THOMAS LEO ASH.

enclosing the corresponding 'po'r-,

